Compass Heads and a Rod Hung by Three Cords
Red-chalk mechanism studies with a large ringed wheel and paired arms
In red chalk (page inverted) Leonardo lays out mechanical studies dominated by a large ringed, cog-like wheel from which two arms rise obliquely, with a smaller ringed device above and a pegged horizontal bar below. The catalogue captions read the drawings as compass heads and as a rod suspended by three cords. The forms explore the joints and fittings of these instruments.
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Ringed wheel with paired rising arms
The central figure is a large circle bordered by a beaded or toothed rim, its hub marked by a small rosette, from which two jointed arms splay upward. A smaller ringed head with a projecting element sits above it. The catalogue names these as heads of compasses.
Rod suspended by three cords
A straight horizontal bar drawn at the foot of the sheet carries a row of short pegs or teeth along its length. The catalogue identifies it as a rod hung by three cords. It reads as a separate device study set apart from the compass heads above.